Hi all here I am again with beer engine questions.
I have recently purchased 2 second hand Angram type CO pumps. They work very well out of the box but seem to ‘groan’ whilst in operation. I thought it may be the springs, but after some lubrication of them, the groaning continues on the downstroke.

I have noticed this happening in some pubs, without seeing if the offending engines were Angrams, anyone have any ideas to stop this? Thanks

Hi all here I am again with beer engine questions.
I have recently purchased 2 second hand Angram type CO pumps. They work very well out of the box but seem to ‘groan’ whilst in operation. I thought it may be the springs, but after some lubrication of them, the groaning continues on the downstroke.

I have noticed this happening in some pubs, without seeing if the offending engines were Angrams, anyone have any ideas to stop this? Thanks

A likely culprit is the "flap" valves in the cylinder. Any handpump would have them. Those valves do wear out or otherwise not effect a very good seal (in bad cases some handpumps will suck beer back from the glass - if the nozzle is submerged as is commonly the case with "swan-neck" or "northern" nozzles - but some pumps can be heard sucking back air too). You can imagine the "flap" will make a noise if it is not sealing, or a bit loose when open - like blowing across a blade of grass held between your thumbs (if you ever did that sort of thing).

The "flap" valves don't have to be worn. They can operate in a less than optimum manner even if new or replaced.